Sigma Seven (Song)
Sigma Seven is only song in the game Sigma Seven. It starts playing after the main menu, once the credits are displayed, and continues playing through the main menu until you start a new game.
Sigma Seven (C64)
The song is rendered on the 6581 chip.
Sigma Seven (CPC)Julian Breeze worked on the ZX Spectrum and Amstrad CPC ports simultaneously, so probably neither port has the "original" version of the song, and they both sound similar.
This port rendered the music on the AY-3-8912.